The bed agglomeration was studied at a laboratory scale by exploring the effect of heating on mixtures containing ash-forming elements (Na, Mg, Al, Si, P, S, K, Ca, Mn, and Fe) and sand. Although some of the elements considered in this work usually appear in bottom ash only at very low contents, the laboratory samples contained excessive amounts to emphasize their role in agglomeration. All samples were analyzed with a scanning electron microscope combined with energy dispersive spectrometry (SEM-EDS) and X-ray powder diffraction (XRD). Coating layers were formed on the sand particles, and we also observed the formation of agglomerates. With an excessive amount of phosphorus in the samples, it seems that phosphates are formed in coating layers and adhesive material instead of silicates, which would be expected in hill-scale FB boiler samples. The simulation of bed agglomerates in the laboratory has turned out to be a useful and fast way to discuss factors governing bed agglomeration.